Szilagyi



Jan. 31, 1956v l. szlLAGYl 2,733,370

SPARK PLUGS Filed July 1l, 1950 2 Sheetswsnee'c l l www' INVENTOR. /sra/A/v Sz/A6 V/ 75H47, M7 n A? frysl. szlgAGYl Jan. 3l, `1956 SPARK PLUGS 2 Sheets-Sheet 2 Filed July ll 1950 INVENTOR. /ST VAN Sz/L A o v/ -mllllllmm MMIII III III lum Will ' Fig. 1.

United States .Patent g r 2,733,370 v"Sinti-snrsii Lian. 31;, issie' i The invention 'relates "to spair'k'pliig's 'for internal com- 'on ines and- -particular ,.ito'ft'he structure fand spark plug electrodes, 'whereby iftduling of the spark plug by carbon is minimized.

The primary object of the invention is the provision of a slit in at least one of the electrodes of the spark plug,V the width of this slit being smaller than the length of the spark gap between the coacting electrodes. Thus due to capillary attraction oil particles will be preferentially caught in the said slit rather than in the gap between the coacting electrodes.

Another object of the invention is the provision of the spark points of the electrodes in or near the smallest cross section of a bore arranged in the lower part of the body of the spark plug, this bore having preferably the shape of a Laval-tube, e. having at one place a restricted cross section enlarging in both directions outward from the said restricted cross section.

A further object of the invention is the provision of an insulating, tube shaped body, surrounding the center electrode and spaced from this electrode so as to form an annular space communicating the lower part of the spark plug and tightly closed at its upper end. The diameter of the center electrode is thus less than the inner diameter of the tube shaped bodyv and during the compression stroke the gas penetrates through the said bore into the tube shaped insulator, while during the explosion stroke the gas ilows in an opposite direction. As the velocity of the gas is the highest in the cross section of the said bore where the spark points are located, the rapid gas stream removes the oil drops caught in the slit of the electrodes at each stroke. Other features of the invention will be apparent to one skilled in the art from the following description taken in connection with the annexed drawings, wherein Fig. 1 is a longitudinal central sectional view of a spark plug embodying the features of the present invention.

Fig. 2 is a bottom plan view of the spark plug of Fig. 3 is a side view of the spark plug according to Fig. l.

Fig. 4 is a longitudinal central sectional view of another embodiment of the invention.

Fig. 5 is a bottom Fig. 4.

Fig. 6 is a side view Fig. 4.

Fig. 7 is a side and partly a sectional view showing a slight modification of the construction of Figs. 1 3.

Fig. 8 is a plan view of the spark plug of Fig. 7. The preferred form of my improved spark plug is shown in Figs. 1-3. In these figures the reference character 1 indicates the lower part of the shell of a spark plug, provided with the usual thread 2. Passing centrally through a bore 3 in this part is the center electrode 5 secured at its upper end in a cylindrical shaped body 4. Between this body 4 and the lower part 1 of the spark plug a tube shaped hollow member 6, preferably of of the spark plug according to with the restricted bore inl plan view of the spark plug of Y 2 vitreossil'ica is provided, the diameter ofthe electrode 5 beingsrnaller thanwthe inner diameter of the -insulating Iiiem'ber'. Thus-the center *electrodefisiplaced in 'faspace 7 `coxnmunieating'with the b ore 3 vin `the lower pait lof the' spark plug'. kflhe tube Yshaped insulating memberis on rits upper end tightly closed by meansfof `a sealing ring-8 and -the *body 4, provided` with 'cooling ins.=10. b" dy 4 fis arranged between the tube shaped .'silica in mberf anda centrejcap 11,. Member 6, body 4 and centre cap `1V1'are.ii1 e`dA in the shown position by a bridle lf2 .pivotally mounted in ythe .lower .part 1 of'the spark plug,l whereby the `pressure exercised; by the bridle may be' adjusted lbs/.means of a screw-.13 .fitted :in fthe-centre cap `11 fand,n havinga lgroove 15 nnits head I-14fin which th mzefrilarr `@faire bridle is is located; Prin .regs @or lzyiridle` '12 are both Aprovided with `an insulating Vcovering '16. i

The bearing body 4 is made of a conducting material, the centre cap 11 of an insulating material, whereby the body 4 serves as a binding nut for proper connection with the external wiring system.

The lower part 1 of the shell as usual, constitutes one pole of the electric circuit, an electrode 17 being mounted upon the shell. This electrode is arranged transversally to the geometrical axis of the bore 3 and comprises two rods 17a and 17b parallel to one another and forming a narrow slit 18, the width of this slit 18 being smaller than the length x of the spark gap between the coacting electrodes 5 and 17. Thus, oil drops are caught by capillary attraction in the slit 18 rather than in the gap x, where they would foul the splug.

In order to remove the oil drops or other deposits out of the slot 18 the bore 3 is shaped like a Laval tube and the spark gap is arranged in the narrowest cross section of the bore. As this bore 3 communicates with the space 7 inside the silica member 6, gas flows into this space 7 through the bore 3 during the compression stroke and flows out during the expansion stroke.

oughly eifective cleaning means, blowing the oil drops out of the slit between the electrodes 17a and 17b. At the same time the pressure of the gas being the lowest around the spark gap the electric resistance in the spark gap is diminished.

The construction shown in Figs. 1, 2 and 3 may be modified as shown in Figs. 4, 5 and 6 for the purpose and 23 is smaller than This gap is arranged in bore 24 formed like a like those shown in Figs. 1- The invention claimed is: 1. A spark plug comprising a shell, an insulated center electrode, a grounded electrode formed of two straight parallel rods extending diametrically across the lower end of the shell and spaced transversely of the shell to form a narrow slit between them of a width less than the length of the spark gap between said center and grounded electrodes.

2. A spark plug according to claim l in whichthe shell has an axial bore therein, thefdiameter of said bore varying along the axis of the bore and the sparkpoints of the electrodes being located in the narrowest section of the said bore. t

3. A spark plug comprising a shell, a hollow tubular member of insulating material, a conductor having a diameter less than the internal diameter of said tubular member and passing through the said member and forming a center electrode, a grounded electrode formed of two straight parallel rods extending diametrically across the lower end of the shell and spaced transversely of the shell to form a narrow slit between them of a width less than the length of the spark gap between said center and 20 grounded'electrodes, said shell having an axially extend- Aingconcal bore therein communicatingat its region of greatest diameter with the interior of said tubular member, andthe spark points 'of said electrodes being located in the region of said conical bore of smallest diameter.

References Cited in the le of this patent UNITED STATES PATENTS 1,067,791 Duffy 'Q July 15, 1913 1,132,811 Walton f Mar. 23, 1915 1,250,160 Good T-, Dec.. 1,81917v 1,425,476 Henkle Q/ Q... Aug.`8,.1922 1,499,921 Goetz July 1, 1924 1,579,060' Barnes et al. Mar. 30, 1926 1,943,674 vWoods Jan. 16, 1 934 2,049,130 Miron July 28, 1936 2,117,216 Ruthardt ..f n May 10, 1938 2,334,204 King Nov. 16, 1943 FOREIGN PATENTS 303,549 Great Britain Jan. 7, 1929 Great Britain Nov. 21, 1932 

